I am an avid succulent collector and enjoy the Genus Pachypodium. I currently grow 5 species namaquanum, brevicaule, inopinatum, griquense and succulentum. There are approximately 25 species mostly from the island of Madagascar with 5 found in South Africa. Its derivation is from Greek (Pachus)- thick , (podion)- foot. Thick-footed.
Pachypodium caudices and branches are thickened with water-storing tissue. When drought/dormancy occurs they rely on these storage organs to sustain them until they begin growing again.
Part of my reason for going to South Africa this past January was to see succulents and all manner of flora quite frankly. I saw the beautiful Pachypodium succulentum in the Eastern Cape of South Africa growing in stony arid soil. It was not in bloom but full leaf . This plant is a Geophyte as its caudex or tuber ( storage organ) is below the soils surface as seen below.
My plant is currently in bloom and is growing into a nice caudifiorm. It is a slow-growing plant but one of the most floriferous of the Genus. The flowers are pink with a red stripe down each petal.